"FSH- and LH- expressing cells during development of the cichlid fish Cichlasoma dimerus: Novel expression of gonadotropins in brain and ovary"

M. PANDOLFI; F. LO NOSTRO; A. SHIMIZU; G. REY VÁZQUEZ; F. MEIJIDE; M. C. MAGGESE

Tampa, Florida, USA

Congreso; 2005 Joint Meeting of Ichthyologists and Herpetologists; 2005

American Society of Ichthyologists and Herpetologists

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) expressing cells were detected in pituitary, brain and ovary of the cichlid fish <i>Cichlasoma dimerus<i> (Perciformes, Acanthopterygii). This detection was carried out by immunohistochemistry (IHC) and Western blot techniques, using antisera of <i>Fundulus heteroclitus<i> (Cyprinodontiformes, Acanthopterygii) against the conservative region of the FSHb and the LHb subunits. The estimated molecular weights, measured by SDS page and western blot were 24 kD for LH (pituitary, brain and ovary) and 19 and 15 kD (pituitary and ovary) and 15 kD (brain) for FSH. In the pituitary, both cell types showed a distribution along mid and ventral zones of the proximal pars distalis (PPD, mid-immunoreactive cells) and along the ventral and dorsal external border of the pars intermedia (PI, high-immunoreactive cells). Double IHC showed that FSH and LH are mainly expressed in different pituitary cells, with the exception of some co-localization observed on the ventral border of the PI. FSH cells were detected in the pituitary around day 21 after hatching (ah) (prior to sex differentiation), while LH cells were detected by day 60 ah (during the sexual differentiation period). FSH and LH neurons were localized in the hypothalamic nucleus lateralis tuberis and their fibers project through the ventral hypothalamus, preoptic area and neurohypophysis. FSH neurons differentiated at the same time that the pituitary FSH cells on day 21 ah, while LH neurons appeared on day 15 ah, days before differentiation of LH pituitary cells. In the ovary, the ir- for both FSH and LH was restricted to the cytoplasm of previtellogenic and early vitellogenic oocytes. These results suggest that the functions of FSH and LH are beyond their well-known effect on gonads and it is possible that they may be related with hypophysotropic, neuromodulator functions (brain derived GtHs) and intraovarian communication (ovary derived GtHs).